How does combustion air enter the cylinder of a two-cycle diesel engine ? Through _______.
A.Cylinder head valves
B.Ports
C.Turbo chargers
D.Bleeder valves
第1题:
第一组: The Wartsila 50DF operates on the lean-bum principle: the mixture of air and gas in the cylinder has more air than is needed for complete combustion. Lean combustion reduces peak temperatures and therefore NOx emissions. Efficiency is increased and higher output is reached while avoiding knocking. Combustion of the lean air-fuel mixture is initiated by injecting a small amount of LFO (pilot fuel) into the cylinder. The pilot fuel is ignited in a conventional diesel process, providing a high-energy ignition source for the main engine. To obtain the best efficiency and lowest emissions, every cylinder is individually controlled to ensure operation at the correct air-fuel ratio and with the correct amount and timing of pilot fuel rejection. Wartsila has developed a special electronic control system to cope with the demanding task of controlling the combustion in each cylinder, and to ensure optimal performance in terms of efficiency and emissions under all conditions by keeping each cylinder within the operating window. Stable and well-controlled combustion also contributes to less mechanical and thermal load on the engine components. Current stringent emission regulations demand the reduction of NOx emissions. In an internal combustion engine this means controlling peak temperature and residence time, which are the main parameters governing NOx formations. In the Wartsila 50DF engine, the air-fuel ratio is very high (typically 2.2). Since the same specific heat quantity released by combustion is used to heat up a larger mass of air, the maximum temperature and consequently NOx formation are lower. The mixture is uniform. throughout the cylinder since the fuel and air are premixed before introduction into the cylinders, which helps to avoid local NOx formation points within the cylinder. Benefiting from this unique feature, NOx emissions from the Wartsila 50DF are extremely and comply with the most stringent existing legislation.
What is the combustion feature of the Wartsila 50DF?
A.Lean air in the cylinder
B.Excessive fuel in the cylinder
C.Excessive air in the cylinder
D.Spark ignition
第2题:
blows out the exhaust gases
supplies oxygen for combustion
cools the valves and cylinder walls
all of the above
第3题:
Control the amount of lube oil burned in the combustion chamber
Transmit heat from the piston to the cylinder liner
Prevent damage to ring groove inserts by acting as a heat dam
Dissipate combustion chamber gas pressure by channeling it through the ring gap
第4题:
delivering more air into the cylinder than it would normally receive during an ordinary charging process
forcing the products of combustion out of the cylinder with the fresh air charge
collecting the air charge at the cleaner
combustion and expansion of hot gas
第5题:
backfire through the air intakes
develop less power under load
have high firing pressures
lift its cylinder relief valves
第6题:
Cylinder head valves
Ports
Turbo chargers
Bleeder valves
第7题:
less fuel will enter the cylinder
lower will be cylinder compression temperatures
more complete will be fuel combustion
more rapid will be the rise in combustion pressure
第8题:
intake valves
carburetor
exhaust ports
injector nozzles
第9题:
it has a longer power stroke
more air gets into the cylinder each stroke
it develops twice as many power strokes at the same speed
higher combustion pressure is developed
第10题:
prolong the ignition delay period
ensure the beginning of fuel injection
thoroughly utilize the air charge
allow controlled fuel combustion
第11题:
air starters
carburetors
natural aspiration
air receivers
第12题:
injection pressure
shape of combustion space
turbulence in combustion space
all of the above
第13题:
Diesel engines obtain combustion air through turbo chargers,blowers,or ______.
A.Air starters
B.Carburetors
C.Natural aspiration
D.Air receivers
第14题:
high compression pressure
low intake air temperature
low exhaust pressure
high scavenge air temperature
第15题:
causes colloid suspension in the cooling water
reduces the capability of the lubrication system
can form pockets which block the flow of coolant through the system
leads to the scuffing of cylinder walls
第16题:
air bottle
air compressor
crank case
combustion chamber
第17题:
fouling turbine
fuel pump faults
lubrication failure
excessive cooling
第18题:
cylinder valves
compression rings
piston skirts
oil rings
第19题:
failure of the fuel pumps
starting air pressure too low
stop valve in air line closed
the turning gear still engaged
第20题:
Combustion does not begin until the piston starts down on the power stroke
Maximum combustion pressure is reached before TDC
Turbulence in the cylinder causes a delay in ignition
Maximum cylinder firing pressure is not developed until the piston passes TDC
第21题:
prevent piston side thrust
prevent engine friction losses
transmit heat from the piston to the cylinder liner
remove oil from the cylinder combustion space
第22题:
high temperatures
low temperatures
wet
dirty
第23题:
a cylinder air charge of higher pressure
increased pumping losses
less valve overlap
reduced blow-by